The purpose of this project is: (1) to investigate the role and functional organization of different brain sites in the integration of the cardiovascular adjustment to exercise and learned modification of cardiovascular functions; (2) to understand the mechanisms of naturally occurring nocturnal hemodynamic patterns and adaptive responses related to modification of those patterns. Monkeys are operantly conditioned to exercise while attenuating the exercise related increase in heart rate. Activation of different sites of the brain related to cardiovascular control can interact with learned attenuation of the tachycardia of exercise.